We report the detection of a planetary companion around HIP 13044 , a metal-poor star on the red Horizontal Branch .
The detection is based on radial velocity observations with FEROS , a high-resolution spectrograph at the 2.2-m MPG/ESO telescope , located at ESO La Silla observatory in Chile .
The periodic radial velocity variation of P = 16.2 days can be distinguished from the periods of the stellar activity indicators .
We computed a minimum planetary mass of 1.25 M _ { \mathrm { Jup } } and an orbital semi-major axis of 0.116 AU for the planet .
This discovery is unique in three aspects : First , it is the first planet detection around a star with a metallicity much lower than few percent of the solar value ; second , the planet host star resides in a stellar evolutionary stage that is still unexplored in the exoplanet surveys ; third , the star HIP 13044 belongs to one of the most significant stellar halo streams in the solar neighborhood , implying an extragalactic origin of the planetary system HIP 13044 in a disrupted former satellite of the Milky Way .